Patent Document 1 discloses a lamp for an automobile, configured to have a multi-reflector structure as the internal structure of the lamp, thereby expanding a beam irradiation range, and to radiate a beam to show a part of a vehicle, thereby making the other people recognize the width and height of the vehicle.
Patent Document 1: Japanese Patent Application Publication No. S63-213203 A
In tunnel-like structures such as tunnels and underpasses, since sunlight is blocked, it's dark. Therefore, in a case where a vehicle runs in a tunnel-like structure, as compared to a case where the vehicle runs outside the tunnel-like structure, it is more difficult for the driver to recognize preceding vehicles. As a result, there is a risk that a driver would miss a preceding vehicle and make the driver's vehicle come too close to the preceding vehicle. Especially, in a case where the preceding vehicle is a small vehicle such as a saddle-ridden type vehicle, the driver is likely to miss the preceding vehicle, and a possibility that the driver's vehicle will come too close to the preceding vehicle increases.
Also, the point of view of a driver of a large vehicle such as a large truck is likely to see a far distance since the driver's seat is at a position high from the road. Therefore, the driver is likely to miss a preceding vehicle running near the driver's vehicle, a saddle-ridden type vehicle hiding behind that preceding vehicle, and the like. As a result, there is a risk that excessive approaching the preceding vehicle, unreasonable pulling over with respect to the saddle-ridden type vehicle, or unreasonable overtaking would occur.
Meanwhile, the lamp for an automobile disclosed in Patent Document 1 has an expanded beam irradiation range, and can irradiate a part of the vehicle body with a beam from the lamp. Therefore, it can be considered that in a case where individual vehicles are equipped with such lamps, as compared to a case where the individual vehicles are not equipped with them, it is easy for the drivers of the individual vehicles to recognize preceding vehicles.
However, although the above-mentioned lamp has the expanded beam irradiation range, that is limited to the vehicle body and a range close to the vehicle body around the vehicle body. Therefore, even in the case where the individual vehicles running in a tunnel-like structure are equipped with the above-mentioned lamps, it may be difficult for the drivers to recognize preceding vehicles as will be described below.
In a case where a plurality of vehicles are running in front of a vehicle of a driver along the traveling direction of the driver's vehicle, a preceding vehicle far from the driver's vehicle may hide behind another preceding vehicle close to the driver's vehicle. At the same time as this, a beam from the lamp mounted on the preceding vehicle far from the driver's vehicle may be blocked by the preceding vehicle close to the driver's vehicle. In this case, it is difficult for the driver to recognize the preceding vehicle far from the driver's vehicle. Especially, in a case where the preceding vehicle far from the driver's vehicle is a saddle-ridden type vehicle, this situation is likely to occur.